The long-range goal of this project is to make a significant contribution to the understanding of the role of chemical processes in the processing (learning) and storage (memory) of information in the central nervous system. Current concepts of the mechanisms of learning suggest that a necessary prerequisite or corollary involves a long lasting modification (structural, physiologic and/or chemical) within the central nervous system which occurs as a direct result of environmental stimuli. The term "plastic changes" has been given to these modifications which have been induced by learning processes. It has been possible for the physiologists and anatomists to design experiments to detect these plastic changes in the nervous system. This project proposes to determine whether it is possible to detect chemical modifications which can be directly correlated with the phenomena reported on by the other disciplines. Our efforts will be most concentrated on a study of the metabolic systems associated with the metabolism, transport, storage and release of neurotransmitters. The study of these systems in individual neurons of Aplysia should provide us with valuable insights for: (a) understanding the cell-specific metabolic specialization associated with the separate neurotransmitter systems; (b) appreciating the general chemical and metabolic properties that distinguish one nerve cell from another. It is quite possible that cell-specific metabolic properties underlie the development of specific patterns of neuronal connectivity. It is equally possible that these metabolic properties represent "molecular sites" of modification as a result of environmental stimuli. By studying the relationship between metabolism and physiological phenomena at the level of single neurons, we hope to be able to detect the chemical correlates of plastic changes observed by neurophysiological techniques.